The present invention relates to a sheet punching apparatus, a sheet finishing apparatus, and an image forming apparatus. More specifically, the present invention relates to a sheet punching apparatus for punching a hole in a sheet, a sheet finishing apparatus provided with the sheet punching apparatus, and an image forming apparatus provided with the sheet punching apparatus or the sheet finishing apparatus.
Generally, an image forming apparatus such as a copier, printer, and facsimile forms an image on a sheet, and the sheet is finished such as being punched with a hole (specifically holes for filing) and being bound in a file binder. In recent years, in order to streamline the finishing process, a sheet punching apparatus for punching a hole in a sheet with an image has become commercially available as a part of an image forming apparatus, a peripheral device, or a device as a stand-alone type independent of an image forming apparatus. Such a sheet punching apparatus is provided with a punch scrap container for storing punch scraps of holes after the holes are punched in sheets.
The punch scraps tend to accumulate at a specific location inside a punch scrap container corresponding to a position of a sheet punching position. Accordingly, in order to prevent the punch scraps from overflowing the container, in an image forming apparatus, a drive source for transporting a sheet may be used as a drive source for vibrating the punch scrap container to level the punch scraps therein. The image forming apparatus may also be provided with an optical sensor for detecting an amount of the punch scraps inside the punch scrap container after the punch scraps are leveled, thereby indicating that the punch scrap container is filled with the punch scraps (refer to Japanese Patent Publication (Kokai) No. 11-139674).
In the apparatus disclosed in Japanese Patent Publication (Kokai) No. 11-139674, it takes a large amount of energy to vibrate the punch scrap container. It is also necessary to provide a drive mechanism for vibrating the container, thereby increasing a size of a sheet punching apparatus. In particular, a sheet transport device and the punch scrap container are arranged away from a drive source, and it is necessary to transmit a driving force to the sheet transport device and the punch scrap container from the common drive source, thereby increasing a size of a transmission mechanism (drive transmission system) and a size of the sheet punching apparatus.
Further, when a sheet is transported and the punch scrap container is vibrated at the same time, it is necessary to increase a load on the drive source, thereby increasing energy consumption and vibration, or making it difficult to transport a sheet properly. If a sheet is transported and the punch scrap container is vibrated at a different timing, it is difficult to improve efficiency of the sheet punching apparatus.
In the apparatus disclosed in Japanese Patent Publication (Kokai) No. 11-139674, even when the paper scraps are leveled with vibration, the scraps may move fluidly inside the punch scrap container, thereby creating an uneven level of the punch scraps. When the optical sensor detects the uneven level of the punch scraps, the optical sensor may erroneously detects that the punch scrap container is full due to the movement of the punch scraps. Also, it detected that the punch scrap container is full after the punch scraps are leveled with vibration. Accordingly, it takes a long time to level the punch scraps, thereby lowering efficiency of the detection.
In view of the problems described above, an object of the present invention is to provide a sheet punching apparatus with a compact structure for efficiently punching a hole in a sheet, a sheet finishing apparatus provided with the sheet punching apparatus, and an image forming apparatus provided with the sheet punching apparatus or the sheet finishing apparatus.
Another object of the present invention is to provide a sheet punching apparatus in which it is possible to detect accurately and efficiently that a punch scrap container becomes full, a sheet finishing apparatus and an image forming apparatus provided with the sheet punching apparatus.
Further objects and advantages of the invention will be apparent from the following description of the invention.